Labourers get advice on how to avoid heatstroke

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Construction workers toiling in the hot sun have a new guide setting out how long they can stay on the job without risking heatstroke.

The guide, drawn up by a research team from Polytechnic University, takes into account different factors including the nature of the job, the worker's fitness and habits, the weather and pollution.

For example, a 45-year-old rebar worker who smokes and drinks occasionally should labour for no longer than 70 minutes when the Observatory's very hot weather warning is in force and the air pollution index is at medium.

The research team found that a worker's heat tolerance time declines by about half an hour for every 10 years of their age. Tolerance time also drops by about five minutes for every one degree Celsius of temperature.

The study also calculated the optimal recovery time for workers to regain their strength before heading out again.

On average, a rebar worker would achieve about 78 per cent recovery after 15 minutes' rest. The longer the break, the better the recovery.

'We aim to provide [the industry with] some findings to decide an optimum resting time [for workers] which won't slow down the construction process and won't jeopardise their health,' said Professor Albert Chan Ping-chuen, who led the research team.

The findings were based on data collected from 39 rebar workers at six construction sites.

But the guidelines could also be adapted to help other workers labouring outdoors during the steamy summer months.

Chan, associate dean of PolyU's faculty of construction and environment, said the team was now turning its attention to designing anti-heat-stress clothing for outdoor workers to help prevent heatstroke.

The clothing would keep workers dry, cool and comfortable while protecting them from UV rays.

The research was supported by the Research Grants Council and the findings were published in the international journal Building and Environment earlier this month.